1. Field of the Invention
The invention relates to the field of sound protection devices, whereby a worker is protected from auditory damage by protecting headset, but is also provided with an auditory warning concerning possible collision with approaching vehicles, machinery or people.
2. Description of the Prior Art
Motegi et al., “Access Alarming Method and Apparatus for Working Vehicle,” U.S. Pat. No. 4,937,795 (1990), describes an access alarm method which is used to detect the distance between a vehicle, such as a road roller, to an object, such as a worker in the proximity of the vehicle. An ultrasonic wave is transmitted by a transmitter worn by the worker and is received by a receiver in the road roller. The received signal is processed to determine the relative position of the vehicle relative to the worker. An alarm is activated and/or the vehicle is braked when the worker comes within the hazard area of the vehicle based on the position and direction of the vehicle's movement.
In a second embodiment of the system, the worker's ultrasonic system provides an output on a continuous basis in order to increase the reaction time of the system. In the embodiment of FIG. 24, the workers helmet 3 is fitted with ultrasonic transmitting and receiving units 5 disposed in a radially spaced configuration for omnidirectional use.
In Motegi the individual is wearing the transponder which the working vehicle detects and ranges. Presumably, the worker remains uninformed and oblivious to the approaching hazard or the near collision event. Motegi thus is subject to the disadvantage that it provides no protection against vehicles or objects not similarly fitted with a transponder and control device. It also fails to warn the worker that he may be in an area of repeated collision hazard.
Russell, “Sonar-Type Sensory Aids,” U.S. Pat. No. 3,321,737 (1967), describes a device to be worn on the body using ultrasonics to detect obstacles. As shown in FIG. 4, the audio output provided to a speaker 24 generates an audio frequency, which varies as a function of the distance of the user and the object with the variation in frequency being in discrete steps. Further, the amplitude of the signal may be very responsive to the rate at which the distance between the user and object closes similar to your own disclosure.
The Russell device is an aid to the blind, provides a personal audio alarm and responds to sonic ranging of general surrounding objects, ostensibly for the purpose of collision avoidance. The audio feedback is varied to determine the distance to the object. The device is directional and therefore provides directionality according to how the user turns or sights the device. The detection and ranging elements are thus focussed, are not omnidirectional, do not provide stereo generation of audio signals indicative of the direction of approach, and thus are not suitable for collision avoidance.
Benjamin, Jr., “Obstacle Detection System for use by Blind Comprising Plural Ranging Channels Mounted on Spectacle Frames,” U.S. Pat. No. 3,654,477 (1972), and Moricca et al., “Polysensory Mobility Aid,” U.S. Pat. No. 3,993,407 (1976), teach devices directed to obstacle detection incorporated in a eyeglass-type structure. This system is incorporated into eyeglass frames as opposed to ear coverings, and thus does not provide any sound protection.
Chambre, “Device to Assist an Operator with Target Acquisition in a Weapons System,” U.S. Pat. No. 4,967,641 (1990), shows a means by which the operator received target information that is being supplied stereophonically to the operator's helmet. Data representing the approach of the object is identified to the helmet wearer whereas an alarm transmitted in stereo gives a subjective sense of direction of the approaching target.
Takeuchi, “Rearward Obstruction Sensing System for Automotive Vehicle,” U.S. Pat. No. 4,528,563, which describes a detection system, although not a personal warning device, shows the use of four speakers through which an alarm signal is provided to the vehicle operator. The warning signal is directed to a particular speaker so that the driver subjectively recognizes the direction of the obstruction in the manner in which we have suggested. Further, the driver can determine the obstruction distance by distinguishing the period of the intermittent alarm signals.
Abst et al., “Vehicular Collision Avoidance Apparatus,” U.S. Pat. No. 5,339,075 (1994), describes a system in which audio signals are provided to a user as a warning in a manner which is indicative of the relative speed and position of the approaching object. Three distinct audible warning tones are provided to indicate a vehicle approaching with greater speed, a vehicle within a predetermined distance but which is receding, and vehicle within a predetermined distance whose relative speed is the same as the driver.
Sasaki et al., “Vehicle Approach Sensing Apparatus,” U.S. Pat. No. 4,694,296 (1987), shows a system in which a warning signal is provided to the user whenever a closing speed of a vehicle exceeds a predetermined value.
What is needed is some type of sound protection system which still allows for omnidirectional and meaningful audio warning of approaching objects.